1. Field of the Invention
This invention relates to a device designed for limiting the speed of boxes or pallets with various load, capable of gravity displacement over a tilted plane having cylinders or rollers.
2. Background and Material Information
Speed limiting devices are generally used in conveying or dynamic storage facilities. In order to control the speed of these boxes or pallets, over a conveyor made up of cylinders or rollers, inertia-type braking devices are known. Such a braking device is described in German patent document DE-U-69 29 711. Such a braking device has a drum fitted with an adhesive coating, which is directly in contact with the box or pallet or indirectly via one or two cylinders, interposed between the box or pallet and the drum.
This known drum is mounted on a shaft, which is parallel to the axis of the conveyor's cylinders and is connected by a bracket to the conveyor's structure. In home position (i.e., in the absence of boxes or pallets) the drum is maintained slightly cantilevered with respect to the conveying plane, using an elastic element. It retracts automatically during the passage of a box or pallet and the elastic element generates a contact pressure between the drum and the box or pallet which causes, under the adherence effect, the rotation of the drum.
When the invention is indirectly mounted, pressure is generated on the movement transmission cylinders, whereas the cylinders, which are mounted with a certain clearance on the structure, are also, in the absence of boxes or pallets, slightly cantilevered with respect to the circulation plane of the boxes or pallets.
The rotation of the drum drives, at a predetermined speed, a braking system via feeders which are brought into rotation by one of several epicycloidal gear trains operably accommodated inside the drum.
At a predetermined linear speed, which ranges from approximately 0.25 to 0.30 m/s, the feeders come into contact with the internal wall of the drum and the whole assembly tends to come to a halt, the assembly retained by the central shaft and, in particular, the first satellite carrier.
The braking device has an absolute braking unit which operates at a predetermined speed ranges from approximately 0.25 to 0.30 m/s. This speed corresponds to the total locking and immobilization speed of the drum. When a load (e.g., a box or a pallet) moves over the tilted plane, it is braked automatically. The efficiency of this braking system depends on the adherence forces between the drum and its driving vector, i.e., the load in case of direct driving or the cylinder(s) in case of indirect driving.